19-1477; Rev 0; 4/99
Low-Power, Serial, 12-Bit DACs with
Force/Sense Voltage Output
The MAX5175/MAX5177 low-power, serial, voltage-output, 12-bit digital-to-analog converters (DACs) feature a
precision output amplifier in a space-saving 16-pin
QSOP package. The MAX5175 operates from a single
+5V supply, and the MAX5177 operates from a single
+3V supply. The output amplifier’s inverting input is
available to allow specific gain configurations, remote
sensing, and high output current capability. This makes
the MAX5175/MAX5177 ideal for a wide range of applications, including industrial process control. Both
devices draw only 260µA of supply current, which
reduces to 1µA in shutdown mode. In addition, the programmable power-up reset feature allows for a userselectable output voltage state of either 0 or midscale.
The 3-wire serial interface is compatible with SPI™,
QSPI™, and MICROWIRE™ standards. An input register
followed by a DAC register provides a double-buffered
input, allowing the registers to be updated independently or simultaneously with a 16-bit serial word. Additional
features include software and hardware shutdown, shutdown lockout, a hardware reset pin, and a reference
input capable of accepting DC and offset AC signals.
These devices provide a programmable digital output
pin for added functionality and a serial-data output pin
for daisy-chaining. All logic inputs are TTL/CMOS compatible and are internally buffered with Schmitt triggers
to allow direct interfacing to optocouplers.
The MAX5175/MAX5177 incorporate a proprietary on-chip
circuit that keeps the output voltage virtually “glitch free,”
limiting the glitches to a few millivolts during power-up.
Both devices come in 16-pin QSOP packages and are
specified for the extended (-40°C to +85°C) temperature
range. The MAX5171/MAX5173 are 14-bit pin-compatible
upgrades to the MAX5175/MAX5177. For pin-compatible
DACs with an internal reference, see the 13-bit
MAX5132/MAX5133 and 12-bit MAX5122/MAX5123.
Features
♦ ±1 LSB INL
♦ 1µA Shutdown Current
♦ “Glitch Free” Output Voltage at Power-Up
♦ Single-Supply Operation
+5V (MAX5175)
+3V (MAX5177)
♦ Full-Scale Output Range
+2.048V (MAX5177, VREF = +1.25V)
+4.096V (MAX5175, VREF = +2.5V)
♦ Rail-to-Rail® Output Amplifier
♦ Adjustable Output Offset
♦ Low THD (-80dB) in Multiplying Operation
♦ SPI/QSPI/MICROWIRE-Compatible 3-Wire
Serial Interface
♦ Programmable Shutdown Mode and Power-Up
Reset (0 or midscale)
♦ Buffered Output Capable of Driving 4–20mA or
5kΩ || 100pF Loads
♦ User-Programmable Digital Output Pin Allows
Serial Control of External Components
♦ 14-Bit Upgrades Available (MAX5171/MAX5173)
Ordering Information
TEMP. RANGE
PIN-PACKAGE
MAX5175AEEE
-40°C to +85°C
16 QSOP
±1
MAX5175BEEE
MAX5177AEEE
MAX5177BEEE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
16 QSOP
16 QSOP
16 QSOP
±2
±2
±4
Pin Configuration
Applications
Digitally Programmable 4–20mA Current Loops
Industrial Process Controls
Digital Offset and Gain Adjustment
Motion Control
Automatic Test Equipment (ATE)
Remote Industrial Controls
µP-Controlled Systems
Functional Diagram appears at end of data sheet.
SPI and QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
INL
(LSB)
PART
TOP VIEW
FB 1
16 VDD
OUT 2
15 N.C.
RS 3
14 REF
PDL 4
CLR 5
MAX5175
MAX5177
13 AGND
12 SHDN
CS 6
11 UPO
DIN 7
10 DOUT
SCLK 8
9
DGND
QSOP
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
MAX5175/MAX5177
General Description
MAX5175/MAX5177
Low-Power, Serial, 12-Bit DACs with
Force/Sense Voltage Output
ABSOLUTE MAXIMUM RATINGS
VDD to AGND, DGND ...............................................-0.3V to +6V
AGND to DGND.....................................................-0.3V to +0.3V
Digital Inputs to DGND.............................................-0.3V to +6V
DOUT, UPO to DGND ................................-0.3V to (VDD + 0.3V)
FB, OUT REF to AGND...............................-0.3V to (VDD + 0.3V)
Maximum Current into Any Pin............................................50mA
Continuous Power Dissipation (TA = +70°C)
16-Pin QSOP (derate 8mW/°C above +70°C)...............667mW
Operating Temperature Range .............................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10sec) .............................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS—MAX5175
(VDD = +5V ±10%, VREF = 2.5V, AGND = DGND, FB = OUT, RL = 5kΩ, CL = 100pF referenced to ground, TA = TMIN to TMAX, unless
otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
STATIC PERFORMANCE
Resolution
12
Integral Nonlinearity (Note 1)
INL
Differential Nonlinearity
DNL
Offset Error (Note 2)
VOS
Gain Error
Power-Supply Rejection Ratio
GE
±1
MAX5175B
±2
±1
mV
LSB
LSB
RL = 5kΩ
-1.6
±8
10
120
Output Thermal Noise Density
LSB
±4
-0.6
f = 100kHz
LSB
±10
RL = ∞
PSRR
Output Noise Voltage
Bits
MAX5175A
µV/V
1
LSBp-p
50
nV/√Hz
REFERENCE INPUT
Reference Input Range
VREF
0
Reference Input Resistance
RREF
18
VDD - 1.4
V
kΩ
MULTIPLYING-MODE PERFORMANCE
Reference -3dB Bandwidth
VREF = 0.5Vp-p + 2.5VDC, slew-rate limited
350
kHz
Reference Feedthrough
VREF = 3.6Vp-p + 1.8VDC, f = 1kHz,
code = all 0s
-84
dB
VREF = 1.4Vp-p + 2.5VDC, f = 10kHz,
code = FFF hex
84
dB
Signal-to-Noise Plus Distortion
Ratio
SINAD
DIGITAL INPUTS
Input High Voltage
VIH
Input Low Voltage
VIL
Input Hysteresis
3
VHYS
Input Leakage Current
IIN
Input Capacitance
CIN
V
0.8
200
VIN = 0 or VDD
0.001
V
mV
±1
8
µA
pF
DIGITAL OUTPUTS
Output High Voltage
VOH
ISOURCE = 2mA
Output Low Voltage
VOL
ISINK = 2mA
2
VDD - 0.5
V
0.13
_______________________________________________________________________________________
0.4
V
Low-Power, Serial, 12-Bit DACs with
Force/Sense Voltage Output
(VDD = +5V ±10%, VREF = 2.5V, AGND = DGND, FB = OUT, RL = 5kΩ, CL = 100pF referenced to ground, TA = TMIN to TMAX, unless
otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DYNAMIC PERFORMANCE
Voltage Output Slew Rate
SR
Output Settling Time
0.6
To ±0.5LSB, from 10mV to full-scale
Output Voltage Swing (Note 3)
0
Current into FB
-0.1
Time Required to Exit Shutdown
CS = VDD; fSCLK = 100kHz, VSCLK = 5Vp-p
Digital Feedthrough
V/µs
12
0
µs
VDD
V
0.1
µA
40
µs
1
nV-s
POWER SUPPLIES
Positive Supply Voltage
VDD
Power-Supply Current (Note 4)
IDD
4.5
Shutdown Current (Note 4)
5.5
V
0.26
0.35
mA
1
10
µA
TIMING CHARACTERISTICS
SCLK Clock Period
tCP
100
ns
SCLK Pulse Width High
tCH
40
ns
SCLK Pulse Width Low
tCL
40
ns
CS Fall to SCLK Rise Setup
Time
tCSS
40
ns
SCLK Rise to CS Rise Hold
Time
tCSH
0
ns
SDI Setup Time
tDS
40
ns
SDI Hold Time
tDH
0
ns
SCLK Rise to DOUT Valid
Propagation Delay
tDO1
CLOAD = 200pF
80
ns
SCLK Fall to DOUT Valid
Propagation Delay
tDO2
CLOAD = 200pF
80
ns
SCLK Rise to CS Fall Delay
tCS0
10
ns
CS Rise to SCLK Rise Hold Time
tCS1
40
ns
CS Pulse Width High
tCSW
100
ns
_______________________________________________________________________________________
3
MAX5175/MAX5177
ELECTRICAL CHARACTERISTICS—MAX5175 (continued)
MAX5175/MAX5177
Low-Power, Serial, 12-Bit DACs with
Force/Sense Voltage Output
ELECTRICAL CHARACTERISTICS—MAX5177
(VDD = +2.7V to +3.6V, VREF = 1.25V, AGND = DGND, FB = OUT, RL = 5kΩ, CL = 100pF referenced to ground, TA = TMIN to TMAX,
unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
STATIC PERFORMANCE
Resolution
12
Bits
MAX5177A
±2
MAX5177B
±4
Integral Nonlinearity (Note 5)
INL
Differential Nonlinearity
DNL
±1
Offset Error (Note 2)
VOS
±10
mV
LSB
LSB
Gain Error
Power-Supply Rejection Ratio
GE
RL = ∞
-0.6
±4
RL = 5kΩ
-1.6
±8
10
120
PSRR
Output Noise Voltage
f = 100kHz
Output Thermal Noise Density
LSB
LSB
µV/V
2
LSBp-p
50
nV/√Hz
REFERENCE
Reference Input Range
VREF
0
Reference Input Resistance
RREF
18
VDD - 1.4
V
kΩ
MULTIPLYING-MODE PERFORMANCE
Reference -3dB Bandwidth
VREF = 0.5Vp-p + 1.25VDC, slew-rate limited
350
kHz
Reference Feedthrough
VREF = 1.6Vp-p + 0.8VDC, f = 1kHz,
code = all 0s
-84
dB
VREF = 0.9Vp-p + 1.25VDC, f = 10kHz,
code = FFF hex
78
dB
Signal-to-Noise Plus Distortion
Ratio
SINAD
DIGITAL INPUTS
Input High Voltage
Input Low Voltage
Input Hysteresis
VIH
2.2
V
VIL
0.8
VHYS
Input Leakage Current
IIN
Input Capacitance
CIN
200
VIN = 0 or VDD
0.001
V
mV
±1
8
µA
pF
DIGITAL OUTPUTS
Output High Voltage
VOH
ISOURCE = 2mA
Output Low Voltage
VOL
ISINK = 2mA
4
VDD - 0.5
V
0.13
_______________________________________________________________________________________
0.4
V
Low-Power, Serial, 12-Bit DACs with
Force/Sense Voltage Output
(VDD = +2.7V to +3.6V, VREF = 1.25V, AGND = DGND, FB = OUT, RL = 5kΩ, CL = 100pF referenced to ground, TA = TMIN to TMAX,
unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DYNAMIC PERFORMANCE
Voltage Output Slew Rate
SR
Output Settling Time
0.6
To ±0.5LSB, from 10mV to full-scale
Output Voltage Swing (Note 3)
0
Current into FB
-0.1
Time Required to Exit Shutdown
CS = VDD, DIN = 50kHz, fSCLK = 100kHz,
VSCLK = 3Vp-p
Digital Feedthrough
V/µs
12
0
µs
VDD
V
0.1
µA
40
µs
1
nV-s
POWER SUPPLIES
Positive Supply Voltage
VDD
Power-Supply Current (Note 4)
IDD
2.7
Shutdown Current (Note 4)
3.6
V
0.26
0.35
mA
1
10
µA
TIMING CHARACTERISTICS
SCLK Clock Period
tCP
150
ns
SCLK Pulse Width High
tCH
75
ns
SCLK Pulse Width Low
tCL
75
ns
CS Fall to SCLK Rise Setup
Time
tCSS
60
ns
SCLK Rise to CS Rise Hold
Time
tCSH
0
ns
SDI Setup Time
tDS
60
ns
SDI Hold Time
tDH
0
ns
SCLK Rise to DOUT Valid
Propagation Delay
tDO1
CLOAD = 200pF
200
ns
SCLK Fall to DOUT Valid
Propagation Delay
tDO2
CLOAD = 200pF
200
ns
SCLK Rise to CS Fall Delay
tCS0
10
ns
CS Rise to SCLK Rise Hold Time
tCS1
75
ns
CS Pulse Width High
tCSW
150
ns
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
INL guaranteed between codes 16 and 4095.
Offset is measured at the code that comes closest to 10mV.
Accuracy is better than 1LSB for VOUT = 10mV to VDD - 180mV. Guaranteed by PSR test on end points.
RL = open and digital inputs are either VDD or DGND.
INL guaranteed between codes 32 and 4095.
_______________________________________________________________________________________
5
MAX5175/MAX5177
ELECTRICAL CHARACTERISTICS—MAX5177 (continued)
Typical Operating Characteristics
(MAX5175: VDD = +5V, VREF = 2.5V; MAX5177: VDD = +3V, VREF = 1.25V; CL = 100pF, FB = OUT, code = FFF hex, TA = +25°C,
unless otherwise noted.)
MAX5175
280
270
260
250
240
230
262
260
258
256
254
252
MAX5175-03
264
1.4
SHUTDOWN SUPPLY CURRENT (µA)
290
266
MAX5175-02
1.3
1.2
1.1
1.0
0.9
250
220
210
0.8
248
4.4
4.6
4.8
5.0
5.2
5.4
5.6
-50
-30
-10
OUTPUT VOLTAGE vs. TEMPERATURE
OUTPUT VOLTAGE (V)
-50
90
-30
-10
10
30
50
TEMPERATURE (°C)
OUTPUT VOLTAGE vs. LOAD RESISTANCE
DYNAMIC RESPONSE
70
90
MAX5175-06
2.5
2.49934
2.49930
-50
70
MAX5175-05
MAX5175-04
2.49938
50
3.0
2.49946
2.49942
30
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
2.49950
10
5V
VCS
(5V/div)
0
2.0
1.5
2.5V
VOUT
(1V/div)
1.0
0.5
10mV
0
-30
-10
10
30
50
TEMPERATURE (°C)
70
90
10
1k
10k
2µs/div
100k
RL (Ω)
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
DYNAMIC RESPONSE
MAX5175-07
-80
2.5V
VOUT
(1V/div)
THD + NOISE (dB)
0
REFERENCE FEEDTHROUGH
MAX5175-08
-78
5V
VCS
(5V/div)
100
0
VREF = 1.8VDC + 3.6Vp-p at f = 1kHz
VOUT/VREF
(12.5dB/div)
MAX5175 toc9
NO-LOAD SUPPLY CURRENT (µA)
300
NO-LOAD SUPPLY CURRENT (µA)
MAX5175-01
310
-82
-84
-86
-88
10mV
-90
-92
2µs/div
10
100
1k
FREQUENCY (Hz)
6
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
NO-LOAD SUPPLY CURRENT
vs. TEMPERATURE
NO-LOAD SUPPLY CURRENT
vs. SUPPLY VOLTAGE
OUTPUT VOLTAGE (V)
MAX5175/MAX5177
Low-Power, Serial, 12-Bit DACs with
Force/Sense Voltage Output
10k
100k
20
FREQUENCY (Hz)
_______________________________________________________________________________________
10k
Low-Power, Serial, 12-Bit DACs with
Force/Sense Voltage Output
MAX5175
FFT PLOT
MAJOR-CARRY TRANSITION
DIGITAL FEEDTHROUGH
VREF = 2.5 VDC + 1.414Vp-p at f = 10kHz
VOUT/VREF
(12.5dB/div)
MAX5175 toc10
MAX5175-11
0
MAX5175-12
VCS
(2V/div)
VOUT
(2mV/div)
VOUT
(100mV/div)
V/SCLK
(5V/div)
20
100k
FREQUENCY (Hz)
400ns/div
AC-COUPLED
START-UP GLITCH
REFERENCE INPUT FREQUENCY RESPONSE
MAX5175-14
MAX5175-13
0
GAIN (dB)
-5
VDD
(1V/div)
-10
-15
VOUT
(10mV/div)
-20
VREF = 0.67Vp-p + 1.25VDC
-25
0
500
1000
1500
2000
2500
50ms/div
3000
AC-COUPLED
FREQUENCY (kHz)
MAX5177
265
260
255
250
245
240
264
262
260
258
256
254
235
230
SUPPLY VOLTAGE (V)
0.58
0.56
0.54
0.52
0.50
0.48
0.46
0.44
252
2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5
MAX5175-17
266
0.60
SHUTDOWN SUPPLY CURRENT (µA)
270
268
MAX5175-16
NO-LOAD SUPPLY CURRENT (µA)
275
NO-LOAD SUPPLY CURRENT (µA)
MAX5175-15
280
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
NO-LOAD SUPPLY CURRENT
vs. TEMPERATURE
NO-LOAD SUPPLY CURRENT
vs. SUPPLY VOLTAGE
-50
-30
-10
10
30
50
TEMPERATURE (°C)
70
90
-50
-30
-10
10
30
50
70
90
TEMPERATURE (°C)
_______________________________________________________________________________________
7
MAX5175/MAX5177
Typical Operating Characteristics (continued)
(MAX5175: VDD = +5V, VREF = 2.5V; MAX5177: VDD = +3V, VREF = 1.25V; CL = 100pF, FB = OUT, code = FFF hex, TA = +25°C,
unless otherwise noted.)
Typical Operating Characteristics (continued)
(MAX5175: VDD = +5V, VREF = 2.5V; MAX5177: VDD = +3V, VREF = 1.25V; CL = 100pF, FB = OUT, code = FFF hex, TA = +25°C,
unless otherwise noted.)
MAX5177
OUTPUT VOLTAGE vs. TEMPERATURE
OUTPUT VOLTAGE vs. RESISTANCE LOAD
MAX5175-19
1.2
OUTPUT VOLTAGE (V)
1.24970
1.24960
1.24950
DYNAMIC RESPONSE
MAX5175-20
1.4
MAX5175-18
1.24980
OUTPUT VOLTAGE (V)
3V
VCS
(3V/div)
0
1.0
0.8
0.6
1.25V
VOUT
(500mV/div)
0.4
1.24940
0.2
1.24930
10mV
0
-30
-10
10
30
50
70
90
10
100
TEMPERATURE (°C)
1k
10k
100k
2µs/div
RL (Ω)
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
DYNAMIC RESPONSE
MAX5175-21
-74
0
-76
1.25V
VOUT
(500mV/div)
REFERENCE FEEDTHROUGH
MAX5175-22
3V
THD + NOISE (dB)
VCS
(3V/div)
-72
0
VREF = 0.8VDC + 1.6Vp-p at f = 1kHz
VOUT/VREF
(12.5dB/div)
MAX5175 toc23
-50
-78
-80
-82
-84
10mV
-86
-88
10
2µs/div
100
1k
10k
20
100k
FREQUENCY (Hz)
10k
FREQUENCY (Hz)
DIGITAL FEEDTHROUGH (SCLK, OUT)
MAX5175/77 toc25
VREF = 1.5VDC + 0.848Vp-p at f = 10kHz
MAJOR-CARRY TRANSITION
VCS
(2V/div)
MAX5175/77 toc26
FFT PLOT
0
MAX5175 toc24
MAX5175/MAX5177
Low-Power, Serial, 12-Bit DACs with
Force/Sense Voltage Output
SCLK
(2V/div)
VOUT/VREF
(12.5dB/div)
VOUT
(100mV/div)
20
8
FREQUENCY (Hz)
OUT
(500µV/div)
100k
AC-COUPLED
5µs/div
2µs/div
AC-COUPLED
_______________________________________________________________________________________
Low-Power, Serial, 12-Bit DACs with
Force/Sense Voltage Output
MAX5177
REFERENCE INPUT FREQUENCY RESPONSE
START-UP GLITCH
MAX5175-28
MAX5175-27
0
GAIN (dB)
-5
VDD
(1V/div)
-10
-15
VOUT
(10mV/div)
AC-COUPLED
-20
VREF = 0.67Vp-p + 1.25VDC
-25
0
500
1000
1500
2000
2500
3000
50ms/div
FREQUENCY (kHz)
Pin Description
PIN
NAME
FUNCTION
1
FB
2
OUT
3
RS
Reset Mode Select (digital input). Connect to VDD to select midscale reset output value. Connect to DGND
to select 0 reset output value.
4
PDL
Power-Down Lockout (digital input). Connect to VDD to allow shutdown. Connect to DGND to disable shutdown.
5
CLR
Clear DAC (digital input). Clears the DAC to its predetermined output state as set by RS.
6
CS
Chip-Select Input (digital input). DIN is ignored when CS is high.
7
DIN
Serial-Data Input (digital input). Data is clocked in on the rising edge of SCLK.
8
SCLK
Serial Clock Input (digital input)
9
DGND
Digital Ground
10
DOUT
Serial-Data Output
11
UPO
12
SHDN
Shutdown (digital input). Pulling SHDN high when PDL = VDD places the chip in shutdown with a maximum
shutdown current of 10µA.
13
AGND
Analog Ground
14
REF
Reference Input. Maximum VREF is VDD - 1.4V.
15
N.C.
No Connect
16
VDD
Positive Supply. Bypass to AGND with a 4.7µF capacitor in parallel with a 0.1µF capacitor.
Feedback Input
Voltage Output. High impedance in shutdown. Output voltage is limited to VDD.
User-Programmable Output. State is set by the serial input.
_______________________________________________________________________________________
9
MAX5175/MAX5177
Typical Operating Characteristics (continued)
(MAX5175: VDD = +5V, VREF = 2.5V; MAX5177: VDD = +3V, VREF = 1.25V; CL = 100pF, FB = OUT, code = FFF hex, TA = +25°C,
unless otherwise noted.)
MAX5175/MAX5177
Low-Power, Serial, 12-Bit DACs with
Force/Sense Voltage Output
Detailed Description
FB
The MAX5175/MAX5177 12-bit, serial, voltage-output
DACs operate with a 3-wire serial interface. These
devices include a 16-bit shift register and a doublebuffered input composed of an input register and a
DAC register (see Functional Diagram). In addition, the
negative terminal of the output amplifier is available.
The DACs are designed with an inverted R-2R ladder
network (Figure 1) that produces a weighted voltage
proportional to the reference voltage.
Reference Inputs
The reference input accepts both AC and DC values with
a voltage range extending from 0 to VDD - 1.4V. The following equation represents the resulting output voltage:
VOUT =
VREF
⋅ N ⋅ GAIN
4096
where N is the numeric value of the DAC’s binary input
code (0 to 4095), VREF is the reference voltage, and
Gain is the externally set voltage gain. The maximum
output voltage is VDD. The reference pin has a minimum impedance of 18kΩ and is code dependent.
Output Amplifier
The MAX5175/MAX5177’s DAC output is internally
buffered by a precision amplifier with a typical slew rate
of 0.6V/µs. Access to the output amplifier’s inverting
input provides flexibility in output gain setting and signal conditioning (see Applications Information).
The output amplifier settles to ±0.5LSB from a full-scale
transition within 12µs, when loaded with 5kΩ in parallel
with 100pF. Loads less than 2kΩ degrade performance.
Shutdown Mode
The MAX5175/MAX5177 feature a software- and hardware-programmable shutdown mode that reduces the
typical supply current to 1µA. Enter shutdown by writing
the appropriate input-control word as shown in Table 1
or by using the hardware shutdown function. In shutdown mode, the reference input and the amplifier output become high impedance and the serial interface
remains active. Data in the input register is saved,
allowing the MAX5175/MAX5177 to recall the prior output state when returning to normal operation. Exit shutdown by reloading the DAC register from the shift
register, by simultaneously loading the input and DAC
registers, or by toggling PDL. When returning from
shutdown, wait 40µs for the output to settle.
10
R
2R
2R
R
2R
OUT
R
2R
2R
MSB
REF
AGND
SHOWN FOR ALL 1s ON DAC
Figure 1. Simplified DAC Circuit Diagram
Power-Down Lockout
Power-down lockout disables the software/hardware
shutdown mode. A high-to-low transition on PDL brings
the device out of shutdown, returning the output to its
previous state.
Shutdown
Pulling SHDN high while PDL is high places the
MAX5175/MAX5177 in shutdown. Pulling SHDN low does
not take the device out of shutdown. A high-to-low transition on PDL or an appropriate command from the serial
data line (see Table 1 for commands) is required to exit
shutdown.
Serial Interface
The 3-wire serial interface is compatible with SPI, QSPI
(Figure 2), and MICROWIRE (Figure 3) interface standards. The 16-bit serial input word consists of two control bits, 12 bits of data (MSB to LSB), and two sub-bits.
The control bits determine the MAX5175/MAX5177’s
response as outlined in Table 1. The digital inputs are
double buffered, which allows any of the following:
• Loading the input register without updating the DAC
register
• Updating the DAC register from the input register
• Updating the input and DAC registers simultaneously.
______________________________________________________________________________________
Low-Power, Serial, 12-Bit DACs with
Force/Sense Voltage Output
• Clock edge on which serial data output (DOUT) is
clocked out
• State of the user-programmable logic output
• Reset state.
Specific commands for setting these are shown in
Table 1.
The general timing diagram in Figure 4 illustrates how
the MAX5175/MAX5177 acquire data. CS must go low
at least tCSS before the rising edge of the serial clock
(SCLK). With CS low, data is clocked into the register
on the rising edge of SCLK. The maximum serial clock
frequency guaranteed for proper operation is 10MHz
for the MAX5175 and 6MHz for the MAX5177. See
Figure 5 for a detailed timing diagram of the serial interface.
Table 1. Serial-Interface Programming Commands
16-BIT SERIAL WORD
FUNCTION
C1
C0
D11..................D0
S1, S0
0
0
12-bit DAC data
00
Load input register; DAC registers are unchanged.
0
1
12-bit DAC data
00
Load input register; DAC registers are updated (start up DAC with
new data).
1
0
xxxx xxxx xxxx
xx
Update DAC register from input register (start up DAC with data
previously stored in the input registers).
1
1
0 0 x x xxxx xxxx
xx
No operation (NOP).
1
1
0 1 x x xxxx xxxx
xx
Shut down DAC (provided PDL = 1).
1
1
1 0 0 x xxxx xxxx
xx
UPO goes low (default).
1
1
1 0 1 x xxxx xxxx
xx
UPO goes high.
1
1
1 1 0 x xxxx xxxx
xx
Mode 1, DOUT clocked out on SCLK’s rising edge.
1
1
1 1 1 x xxxx xxxx
xx
Mode 0, DOUT clocked out on SCLK’s falling edge (default).
+5V
SS
DIN
MAX5175
MAX5177
SCLK
CS
MOSI
SCK
MICROWIRE
PORT
MAX5175
MAX5177
SCLK
SK
DIN
SO
CS
I/O
SPI/QSPI
PORT
I/O
CPOL = 0, CPHA = 0
CPOL = 0, CPHA = 0
Figure 2. Connections for SPI/QSPI Standards
Figure 3. Connections for MICROWIRE
______________________________________________________________________________________
11
MAX5175/MAX5177
The MAX5175/MAX5177 accept one 16-bit packet or
two 8-bit packets sent while CS remains low. The
devices allow the following to be configured:
MAX5175/MAX5177
Low-Power, Serial, 12-Bit DACs with
Force/Sense Voltage Output
CS
COMMAND
EXECUTED
SCLK
1
DIN
C2
8
C1
C0
D9
D8
D7
D6
D5
9
D4
16
D3
D2
D1
D0
S2
S1
S0
Figure 4. Serial-Interface Timing Diagram
tCSW
CS
tCSO
tCSS
tCSH
tCS1
SCLK
tCH
tCL
tCP
DIN
tDS
tD01
tD02
tDH
DOUT
Figure 5. Detailed Serial-Interface Timing Diagram
Serial-Data Output (DOUT)
The serial-data output (DOUT) is the internal shift register’s output and allows for daisy-chaining of multiple
devices as well as data readback (see Applications
Information). By default upon start-up, data shifts out of
DOUT on the serial clock’s rising edge (Mode 0) and
provides a lag of 16 clock cycles, thus maintaining SPI,
QSPI, and MICROWIRE compatibility. However, if the
device is programmed for Mode 1, then the output data
lags DIN by 16.5 clock cycles and is clocked out on the
serial clock’s rising edge. During shutdown, DOUT
retains its last digital state prior to shutdown.
When CLR is pulled low, UPO will reset to its programmed default state. See Table 1 for specific commands to control the UPO.
Reset (RS) and Clear (CLR)
The MAX5175/MAX5177 offers a clear pin (CLR) which
resets the output voltage. If RST = DGND, then CLR
resets the output voltage to the minimum voltage (0 if
no offset is introduced). If RST = VDD, then CLR resets
the output voltage to midscale. In either case, CLR will
reset UPO to its programmed default state.
User-Programmable Logic Output (UPO)
The UPO allows control of an external device through
the serial interface, thereby reducing the number of
microcontroller I/O pins required. During power-down,
this output will retain its digital state prior to shutdown.
12
______________________________________________________________________________________
Low-Power, Serial, 12-Bit DACs with
Force/Sense Voltage Output
Unipolar Output
Figure 6 shows the MAX5175/MAX5177 configured for
unipolar, rail-to-rail operation with a gain of +2V/V.
Table 2 lists the codes for unipolar output voltages. The
output voltage is limited to VDD.
Bipolar Output
Figure 7 shows the MAX5175/MAX5177 configured for
bipolar output operation. The output voltage is given by
the following equation (FB = OUT):
2N
VOUT = VREF
− 1
4096
where N represents the numeric value of the DAC’s
binary input code and VREF is the voltage of the external reference. Table 3 shows digital codes and the corresponding output voltage for Figure 7’s circuit.
Daisy-Chaining Devices
The serial data output pin (DOUT) allows multiple
MAX5175/MAX5177s to be daisy-chained together as
shown in Figure 8. The advantage of this is that only
two lines are needed to control all of the DACs on the
line. The disadvantage is that it takes n commands to
program the DACs. Figure 9 shows several MAX5175/
MAX5177s sharing one common DIN signal line. In this
configuration the data bus is common to all devices;
however, more I/O lines are required because each
device needs a dedicated CS line. The advantage of
this configuration is that only one command is needed
to program any DAC.
10k
10k
REF
MAX5175
MAX5177
+5V/+3.3V
+5V/+3.3V
REF
VDD
VDD
10k
FB
V+
FB
VOUT
10k
DAC
DAC
OUT
OUT
V-
MAX5175
MAX5177
GND
GND
R1 = R2 = 10kΩ ± 0.1%
Figure 6. Unipolar Output Circuit (Rail-to-Rail)
Figure 7. Bipolar Output Circuit
Table 2. Unipolar Code Table (Circuit of
Figure 6)
Table 3. Bipolar Code Table (Circuit of
Figure 7)
DAC CONTENTS
MSB
LSB
ANALOG OUTPUT
DAC CONTENTS
MSB
LSB
ANALOG OUTPUT
11 1111 1111 11 (00)
2 · VREF (4095/4096)
11 1111 1111 11 (00)
+VREF [(2 · 4095/4096) - 1]
10 0000 0000 01 (00)
2 · VREF (2049/4096)
10 0000 0000 01 (00)
+VREF [(2 · 2049/4096) - 1]
10 0000 0000 00 (00)
2 · VREF (2048/4096)
10 0000 0000 00 (00)
+VREF [(2 · 2048/4096) - 1]
01 1111 1111 11 (00)
2 · VREF (2047/4096)
01 1111 1111 11 (00)
+VREF [(2 · 2047/4096) - 1]
00 0000 0000 01 (00)
2 · VREF (1/4096)
00 0000 0000 01 (00)
+VREF [(2 · 1/4096) - 1]
00 0000 0000 00 (00)
0
00 0000 0000 00 (00)
-VREF
______________________________________________________________________________________
13
MAX5175/MAX5177
Applications Information
MAX5175/MAX5177
Low-Power, Serial, 12-Bit DACs with
Force/Sense Voltage Output
SCLK
SCLK
MAX5175
MAX5177
DIN
DOUT
CS
SCLK
MAX5175
MAX5177
DIN
DOUT
CS
MAX5175
MAX5177
DOUT
DIN
CS
TO OTHER
SERIAL DEVICES
Figure 8. Daisy-Chaining MAX5175/MAX5177s
DIN
SCLK
CS1
CS2
TO OTHER
SERIAL DEVICES
CS3
CS
CS
MAX5175
MAX5177
CS
MAX5175
MAX5177
MAX5175
MAX5177
SCLK
SCLK
SCLK
DIN
DIN
DIN
Figure 9. Multiple MAX5175/MAX5177s Sharing Common DIN and SCLK Lines
14
______________________________________________________________________________________
Low-Power, Serial, 12-Bit DACs with
Force/Sense Voltage Output
Digitally Programmable
Current Source
The circuit of Figure 11 places an NPN transistor
(2N3904 or similar) within the op amp feedback loop to
implement a digitally programmable, unidirectional current source. The output current is calculated with the
following equation:
IOUT =
VREF
R
⋅
⋅
N
4096
power-supply source. Connect DGND and AGND pins
together at the IC. The best ground connection is
achieved by connecting the DAC’s DGND and AGND
pins together and connecting that point to the system
analog ground plane. If the DAC’s DGND is connected
to the system digital ground, digital noise may infiltrate
the DAC’s analog portion.
Bypass the power supply with a 4.7µF capacitor in parallel with a 0.1µF capacitor to AGND. Minimize capacitor lead lengths to reduce inductance. If noise
becomes an issue, use shielding and/or ferrite beads to
increase isolation.
In order to maintain INL and DNL performance, as well
as gain drift, it is extremely important to provide the
lowest possible reference output impedance at the
DAC reference input pin. INL degrades if the series
resistance on the REF pin exceeds 0.1Ω. The same
consideration must be made for the AGND pin.
where N is the numeric value of the DAC’s binary input
code and R is the sense resistor shown in Figure 11.
Power-Supply and Layout Considerations
Wire-wrap boards are not recommended. For optimum
system performance, use printed circuit boards with
separate analog and digital ground planes. Connect
the two ground planes together at the low-impedance
+5V/
+3.3V
AC
REFERENCE
INPUT
+5V/+3.3V
R1
+5V/+3.3V REF
MAX495
VDD
VL
DAC
500mVp-p
R1
REF
MAX5175
MAX5177
IOUT
OUT
VDD
2N3904
FB
DAC
OUT
GND
R
MAX5175
MAX5177 GND
Figure 10. AC Reference Input Circuit
Figure 11. Digitally Programmable Current Source
______________________________________________________________________________________
15
MAX5175/MAX5177
Using an AC Reference
The MAX5175/MAX5177 accept reference voltages
containing AC components, as long as the reference
voltage remains between 0 and VDD - 1.4V. Figure 10
shows a technique for applying a sine-wave signal to
REF. The reference voltage must remain above AGND.
Functional Diagram
Chip Information
TRANSISTOR COUNT: 3457
VDD AGND DGND
CS DIN SCLK
PDL
SHDN
RS
CLR
SERIAL
CONTROL
16-BIT
SHIFT
REGISTER
DECODE
CONTROL
INPUT
REGISTER
DAC
REGISTER
DOUT
LOGIC
OUTPUT
MAX5175
MAX5177
UPO
FB
OUT
DAC
REF
Package Information
QSOP.EPS
MAX5175/MAX5177
Low-Power, Serial, 12-Bit DACs with
Force/Sense Voltage Output
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1999 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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